Knit Fabric With Electrical Components

ABSTRACT

Conductive yarns in a knitted fabric may include insulating cores covered with metal layers that form signal paths. Open circuits may be formed in the yarns by removing metal from the insulating cores at selected locations within the yarns. The fabric may be formed from rows of interlocked loops of the yarn. The open circuits may be located on the loops so that each loop with an open circuit has a first segment of the metal layer that is separated from a second segment of the layer by a portion of the loop from which the metal layer has been removed. Each electrical component may have terminals that span a respective one of the open circuits and that are shorted respectively to the metal of the first and second segments.

This application is a continuation of U.S. patent application Ser. No.15/441,021, filed on Feb. 23, 2017, which claims the benefit of U.S.provisional patent application No. 62/300,236, filed on Feb. 26, 2016,which are hereby incorporated by reference herein in their entireties.This application claims the benefit of and claims priority to U.S.patent application Ser. No. 15/441,021 and U.S. provisional patentapplication No. 62/300,236.

FIELD

This relates generally to fabric-based items and, more particularly, tofabric-based items with electrical components.

BACKGROUND

It may be desirable to form bags, furniture, clothing, and other itemsfrom materials such as fabric. Fabric-based items generally do notinclude electrical components. It may be desirable, however, toincorporate electrical components into a fabric-based item to provide auser of a fabric-based item with enhanced functionality.

It can be challenging to incorporate electrical components into afabric-based item. Fabric is flexible, so it can be difficult to mountstructures to fabric. Electrical components must be coupled to signalpaths, but it can be difficult to satisfactorily attach components toconductive strands of material.

SUMMARY

A fabric-based item may include fabric such as knitted fabric. Theknitted fabric may be formed from conductive yarns and insulating yarns.Conductive yarns may form signal paths and may include insulating corescovered with conductive coatings such as metal coatings.

Open circuits may be formed in the yarns by removing metal from theinsulating cores at selected locations within the yarns. Each loop withan open circuit will have a first portion of the metal that iselectrically isolated from a second portion of the metal by a gap.Electrical components can be coupled to loops. Each electrical componentmay span a respective open circuit in a loop and may have a firstterminal that is coupled to the first portion of metal in the loop and asecond terminal that is coupled to the second portion of metal in theloop.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an illustrative fabric-based item inaccordance with an embodiment.

FIG. 2 is a top view of illustrative knitted fabric of the type that maybe provided with electrical components in accordance with an embodiment.

FIG. 3 is a diagram of an illustrative knitting system in accordancewith an embodiment.

FIG. 4 shows how a latch needle may hold a knit loop of yarn in a fabricin accordance with an embodiment.

FIG. 5 shows how the latch in the needle of FIG. 4 may be opened as theneedle is advanced through the loop in accordance with an embodiment.

FIG. 6 shows how a component mounting tool may be advanced towards aloop in accordance with an embodiment.

FIG. 7 shows how a hook on the component mounting tool may hold the loopin accordance with an embodiment.

FIG. 10 shows how an electrical component may be mounted to a loop inaccordance with an embodiment.

FIG. 11 shows how the needle may be introduced to the loop while thecomponent mounting tool is holding the loop in accordance with anembodiment.

FIG. 12 shows how the component mounting tool may be retracted while theneedle is holding the loop in accordance with an embodiment.

FIG. 13 shows how the needle may be advanced after retracting thecomponent mounting tool in accordance with an embodiment.

FIG. 14 is a diagram showing how a hook on the needle may receive a yarnin accordance with an embodiment.

FIGS. 15, 16, 17, and 18 are diagrams showing how the hook with thereceived yarn may be used to form a new loop in accordance with anembodiment.

FIGS. 19, 20, 21, and 22 show how a component mounting tool with asheath or other structures for forming an open circuit may have a hookthat forms a loop in accordance with an embodiment.

FIGS. 23, 24, and 25 show how an open circuit may be formed in the loopby removing a metal coating layer from a portion of a dielectric core inaccordance with an embodiment.

FIGS. 26, 27, 28, and 29 show how a component may be mounted to the loopin a location that spans the open circuit in accordance with anembodiment.

FIGS. 30, 31, 32, 33, 34, and 35 show how an electrical component can beattached to a loop that is placed behind another loop in a knit fabricin accordance with an embodiment.

DETAILED DESCRIPTION

Items such as item 10 of FIG. 1 may be based on fabric. Item 10 may bean electronic device or an accessory for an electronic device such as alaptop computer, a computer monitor containing an embedded computer, atablet computer, a cellular telephone, a media player, or other handheldor portable electronic device, a smaller device such as a wristwatchdevice, a pendant device, a headphone or earpiece device, a deviceembedded in eyeglasses or other equipment worn on a user's head, orother wearable or miniature device, a television, a computer displaythat does not contain an embedded computer, a gaming device, anavigation device, an embedded system such as a system in whichfabric-based item 10 is mounted in a kiosk, in an automobile, airplane,or other vehicle, other electronic equipment, or equipment thatimplements the functionality of two or more of these devices. Ifdesired, item 10 may be a removable external case for electronicequipment, may be a strap, may be a wrist band or head band, may be aremovable cover for a device, may be a case or bag that has straps orthat has other structures to receive and carry electronic equipment andother items, may be a necklace or arm band, may be a wallet, sleeve,pocket, or other structure into which electronic equipment or otheritems may be inserted, may be part of a chair, sofa, or other seating(e.g., cushions or other seating structures), may be part of an item ofclothing or other wearable item (e.g., a hat, belt, wrist band,headband, shirt, pants, shoes, etc.), or may be any other suitablefabric-based item.

Item 10 may include intertwined strands of material (yarns) that formfabric 12. Fabric 12 may form all or part of a housing wall or otherlayer in an electronic device, may form internal structures in anelectronic device, or may form other fabric-based structures. Item 10may be soft (e.g., item 10 may have a fabric surface that yields to alight touch), may have a rigid feel (e.g., the surface of item 10 may beformed from a stiff fabric), may be coarse, may be smooth, may have ribsor other patterned textures, and/or may be formed as part of a devicethat has portions formed from non-fabric structures of plastic, metal,glass, crystalline materials, ceramics, or other materials.

The strands of material in fabric 12, which may sometimes be referred toherein as yarns, may be single-filament strands (sometimes referred toas fibers or monofilaments) or may be strands of material formed byintertwining multiple monofilaments of material together.

The yarns in fabric 12 may be formed from polymer, metal, glass,graphite, ceramic, natural materials such as cotton or bamboo, or otherorganic and/or inorganic materials and combinations of these materials.Conductive coatings such as metal coatings may be formed onnon-conductive material. For example, plastic yarns in fabric 12 may becoated with metal to make them conductive. Reflective coatings such asmetal coatings may be applied to make yarns reflective. Yarns may beformed from bare metal wires or metal wire intertwined with insulatingmonofilaments (as examples). Bare metal strands and strands of polymercovered with conductive coatings may be provided with insulating polymerjackets.

Yarn may be intertwined to form fabric 12 using intertwining equipmentsuch as weaving equipment, knitting equipment, or braiding equipment.Intertwined yarn may, for example, form knitted fabric. Conductive yarnand insulating yarn may be woven, knit, braided, or otherwiseintertwined to form contact pads that can be electrically coupled toconductive structures in item 10 such as the contact pads of anelectrical component.

Conductive yarn and insulating yarn may also be woven, knit, orotherwise intertwined to form conductive paths. The conductive paths maybe used in forming signal paths (e.g., signal buses, power lines, etc.),may be used in forming part of a capacitive touch sensor electrode, aresistive touch sensor electrode, or other input-output device, or maybe used in forming other patterned conductive structures. Conductivestructures in fabric 12 may be used in carrying power signals, digitalsignals, analog signals, sensor signals, control signals, data, inputsignals, output signals, or other suitable electrical signals.

Item 10 may include additional mechanical structures 14 such as polymerbinder to hold yarns in fabric 12 together, support structures such asframe members, housing structures (e.g., an electronic device housing),and other mechanical structures.

To enhance mechanical robustness and electrical conductivity atyarn-to-yarn connections, additional structures and materials (e.g.,solder, crimped metal connections, welds, conductive adhesive such asanisotropic conductive film and other conductive adhesive,non-conductive adhesive, fasteners, etc.) may be used to help formyarn-to-yarn connections. These yarn-to-yarn connections may be formedwhere yarns cross each other perpendicularly or at other yarnintersections where connections are desired. Insulating material can beinterposed between intersecting conductive yarns at locations in whichit is not desired to form a yarn-to-yarn connection. The insulatingmaterial may be plastic or other dielectric, may include an insulatingyarn or a conductive yarn with an insulating coating, etc. Solderconnections may be formed between conductive yarns by melting solder sothat the solder flows over conductive yarns. The solder may be meltedusing an inductive soldering head to heat the solder, using a reflowoven to heat the solder, using a laser or hot bar to heat the solder, orusing other soldering equipment. During soldering, outer dielectriccoating layers (e.g., outer polymer layers) may be melted away in thepresence of molten solder, thereby allowing underlying metal yarns to besoldered together.

Circuitry 16 may be included in item 10. Circuitry 16 may includeelectrical components that are coupled to fabric 12, electricalcomponents that are housed within an enclosure formed by fabric 12,electrical components that are attached to fabric 12 using welds, solderjoints, conductive adhesive bonds, crimped connections, or otherelectrical and/or mechanical bonds. Circuitry 16 may include metalstructures for carrying current, electrical components such asintegrated circuits, light-emitting diodes, sensors, and otherelectrical devices. Control circuitry in circuitry 16 may be used tocontrol the operation of item 10.

Item 10 may interact with electronic equipment or other additional items18. Items 18 may be attached to item 10 or item 10 and item 18 may beseparate items that are configured to operate with each other (e.g.,when one item is a case and the other is a device that fits within thecase, etc.). Control circuitry in circuitry 16 may be used to supportcommunications with item 18 and/or other devices. Circuitry 16 mayinclude antennas and other structures for supporting wirelesscommunications with item 18. Item 18 may also interact with item 10using a wired communications link or other connection that allowsinformation to be exchanged.

In some situations, item 18 may be an electronic device such as acellular telephone, computer, or other portable electronic device anditem 10 may form a cover, case, bag, item of clothing, or otherstructure that receives the electronic device in a pocket, an interiorcavity, or other portion of item 10. In other situations, item 18 may bea wristwatch device or other electronic device and item 10 may be astrap or other fabric-based item that is attached to item 18 (e.g., item10 and item 18 may together form a fabric-based item such as awristwatch with a strap). In still other situations, item 10 may be anelectronic device, fabric 12 may be used in forming the electronicdevice, and additional items 18 may include accessories or other devicesthat interact with item 10. Signal paths formed from conductive yarnsmay be used to route signals in item 10 and/or item(s) 18.

The fabric that makes up item 10 may be formed from multifilament and/ormonofilament yarns (strands) that are intertwined using any suitableintertwining equipment. With one suitable arrangement, which maysometimes be described herein as an example, fabric 12 may be knittedfabric formed using a knitting machine. A top view of illustrativeknitted fabric 12 is shown in FIG. 2. In the illustrative configurationof FIG. 2, fabric 12 has a single layer of knitted yarns 24. Otherfabric constructions may be used for fabric 12 if desired.

As shown in FIG. 2, fabric 12 may include yarns 24 or other strands ofmaterial that form horizontally extending rows of interlocking loops(courses 22) and vertically extending wales 20. Some or all of yarns 24in fabric 12 such as yarn 24 in course 22′ in the example of FIG. 2 maybe conductive.

Some or all of the loops of conductive yarn in fabric 12 may be providedwith electrical components such as illustrative component 26. Componentsin fabric 12 such as component 26 may be light-based components (e.g.,light-emitting diodes and/or light detectors), may be sensors that sensetemperature, pressure, force, capacitance, touch, magnetic fieldstrength, motion, other suitable sensors, integrated circuits withsensors and/or light-based components, integrated circuits withcommunications circuitry and/or control circuitry, and/or otherelectrical devices.

Components such as component 26 may have any suitable number ofterminals. For example, component 26 may have a pair of terminals suchas terminals 28. Component 26 may be mounted to yarn loop 30 so that afirst of terminals 28 is electrically shorted to yarn loop portion 30-1and a second of terminals 28 is electrically shorted to yarn loopportion 30-2. For example, solder or other conductive material may beused to couple terminals 28 to metal in yarn portions 30-1 and 30-1.

The metal or other conductive material of yarn 24 in course 22′ may beselectively removed in the vicinity of component 26 between portions30-1 and 30-2 to create an open circuit such as open circuit 34. In thepresence of open circuit 34, signals can pass through component 26(i.e., signals can pass from one terminal of component 26 to the other),but will not pass through the portion of loop 30 that extends betweenyarn loop portion 30-1 and yarn loop portion 30-2. The formation of opencircuit 34 therefore ensures that terminals 28 will not be shorted toeach other by yarn 24 and allows component 26 to operate satisfactorily.Control circuitry in circuitry 16 (FIG. 1) may be used in controllingthe application of signals to component 26 via yarn 24.

Knitted fabric such as knitted fabric 12 of FIG. 2 may be formed usingany suitable knitting equipment. An illustrative knitting system forforming fabric 12 is shown in FIG. 3. As shown in FIG. 3, knittingequipment such as knitting system 50 may include a yarn source such asyarn source 40. Yarn source 40 may include a creel with spools of yarn24. Knitting elements 42 may be used to knit yarn 24 into knitted fabric12 while forming open circuits 34 and attaching electrical components 26to selected loops of yarn 24, as described in connection with FIG. 2.Knitted fabric 12 may be gathered on drums or other take-down equipment48.

Knitting elements 42 may include yarn guide structures such as feeders44 that guide yarn 24 towards needles and other equipment 46. Equipment46 may include latch needles or needles of other types, may includefeeders for mounting components 26 on yarn 24, and may include cuttingtools or other equipment for forming open circuits in yarn 24 (see,e.g., open circuit 34 of FIG. 2). Equipment 46 may include camstructures and other structures for manipulating the positions ofneedles, component mounting feeders, and/or cutting tools or other toolsfor open circuit formation. The needles, feeders, and tools for formingopen circuits in yarn 24 may be implemented as separately adjustablecomponents or the functionality of two or more of these tools may becombined in equipment 46. For example, a component feeder may includeopen circuit formation structures such as cutting structures forselectively removing metal from yarn 24. Equipment such as feeders 44and equipment 46 (i.e., knitting elements 42) may sometimes be referredto as knitting equipment, knitting and component mounting equipment,equipment for knitting, component mounting, and open circuit formation,etc.

The use of a knitting system such as knitting system 50 of FIG. 3 toknit fabric 12 with components 26 and open circuits 34 is described inthe examples of FIGS. 4-35. Other techniques for forming open circuits34 and for mounting components 26 to loops in fabric 12 may be used, ifdesired.

FIG. 4-18 show how system 50 may be used to knit fabric 12 whileinstalling components 26 onto loops 30 of fabric 26. In the drawings ofFIGS. 4-18, latch needle 54 and component mounting tool 68 (e.g., one ofneedles 46 and one of the component feeders of FIG. 3) are used to knityarn 24 into fabric 12 while attaching components 26. As shown in FIG.4, latch needle 54 includes a stem (shaft) such as stem 56 having aprotruding portion that forms butt 58. Latch 60 is mounted to stem 56using pivot 62. Latch needle 54 has a hook such as hook 64 that isformed from a bent tip portion of stem 56. Latch 60 may be moved betweena closed position (as shown in FIG. 4) and an open position by pivotinglatch 60 about pivot 62.

In the needle position of FIG. 4, loop 30 has been formed by needle 54,latch 60 is closed, and loop 30 is held in closed hook 64.

As shown in FIG. 5, as needle 54 is advanced in direction 66, loop 30presses against latch 60 and opens latch 60.

Equipment 46 may include component mounting tools such as componentmounting tool 68 of FIG. 6. Component mounting tool 68 may have a shaftsuch as shaft 70. Hook 72 may be formed at the end of shaft 70.Component mounting tool 68 may have component mounting structures fordispensing components 26 and attaching the terminals of components 26 toyarn 24. Tool 68 may, for example, include positioning equipment formoving components 26 into place and may have electrical connectionformation equipment for forming electrical connections betweencomponents 26 and yarn 24. The positioning equipment may includestructures that are powered by pressurized air, by vacuum suction, byelectromagnetic actuators, by cams and other structures that converttranslating movement of equipment such as needles, component feeders,and cutting tools into vertical movement, by electromagnets, and/or byother structures for positioning components 26 on yarn 24. Theelectrical connection formation equipment may include equipment forforming solder connections, welds, and cured conductive adhesiveconnections such as hot bar soldering structures, reflow ovenstructures, heat lamps, lasers, and other sources of heat and/orequipment for dispensing solder, adhesive, etc.

As shown in FIG. 7, when component mounting tool 68 is advanced indirection 74, hook 72 of component mounting tool 68 may engage loop 30.

Once hook 72 has grasped the yarn of loop 30, needle 54 may be retractedin direction 76, causing loop 30 to press against latch 60 and therebyclose latch 60 as shown in FIG. 8.

As shown in FIG. 9, after needle 54 has been completely retracted indirection 76, needle 54 will be clear of loop 30 and loop 30 will beheld in place by hook 72 of component mounting tool 68 rather than hook64 of needle 54.

As shown in FIG. 10, component mounting tool 68 may couple a component26 to loop 30 (e.g., using solder, welds, conductive adhesive, etc.)while hook 72 is holding loop 30, so that terminals 28 of component 26form electrical connections to the left and right halves of loop 30, asdescribed in connection with FIG. 2. An open circuit such as opencircuit 34 of FIG. 2 may then be formed in loop 30, as described in moredetail in connection with FIGS. 19-29.

After mounting component 26 to loop 30 (and forming open circuit 34) asshown in FIG. 10, needle 54 can again be advanced in direction 66, asshown in FIG. 11. This causes hook 64 to pass through loop 30 and causeslatch 60 to open as the yarn of loop 30 presses against latch 60.

As shown in FIG. 12, needle 54 may hold loop 30 in position whilecomponent mounting tool 68 is retracted in direction 78.

After retracting component mounting tool 68, needle 54 may be advancedfarther in direction 66 until butt 58 presses against loop 30, as shownin FIG. 13. Another yarn 24 may then be received by hook 64 of needle54, as shown in FIG. 14.

Retraction of needle 54 in direction 76 cause the yarn of loop 30 topress against latch 60, thereby closing latch 60 against hook 64 toretain the newly received yarn 24 within hook 64, as shown in FIG. 15.

Further retraction of needle 54 in direction 76 causes latch 60, hook64, and the yarn held by hook 64 to pass through loop 30, as shown inFIG. 16. Needle 54 may then be advanced in direction 66 to form a newloop of yarn 24 such as new loop 30N of FIG. 17. When needle 54 reachesthe position of FIG. 18, a knitting cycle has been completed (i.e., thefabric and needle configuration of FIG. 18 is the same as that of FIG.4). Further cycles may be performed (with our without component mountingusing tool 68) until the knitting of fabric 12 is complete.

Open circuits such as open circuit 34 of FIG. 2 may be formed during theknitting operations of FIGS. 4-16. Open circuit formation operations areillustrated separately in FIGS. 19-29 for clarity.

When forming fabric 12, some of yarns 24 may be conductive (e.g., thoseyarns onto which it is desired to mount components 26). Remaining yarns24 may be either conductive or non-conductive. As shown in FIG. 19,conductive yarn 24 in loop 30 may be formed using an insulating portionsuch as insulating core 84 and a conductive portion such as metal layer82 or other conductive coating. Strands of material in fabric 12 mayhave a single filament (as shown by yarn 24 in FIG. 19) or may havemultiple filaments.

Component mounting tool 68 may include open circuit formationcapabilities. For example, conductive yarns may have insulating polymercores or other strands of dielectric covered with a conductive metalcoating. Tool 68 may include a metal remover such as metal remover 80.Metal remover 80 may use heat, light (e.g., laser light), electricity,abrasion, cutting (wire stripping motions), or other suitable techniquesto selectively remove a portion of the conductive metal coating awayfrom an insulating polymer core in the yarn of loop 30 to form opencircuit 34. As an example, metal remover 80 may be formed from a metalsheath with a sharp leading edge such as cutting edge 86 in the exampleof FIG. 19 that can advance towards hook 72 at the end of shaft 70 oftool 68 or that can retract away from hook 72. The use of a tool such ascomponent mounting tool (and open circuit formation tool) 68 of FIG. 19may sometimes be described herein as an example. In general, equipment46 of system 50 may use any suitable tool for attaching components 26 toloops 30 and for forming open circuits 34 in loops 30. Tool 68 of FIG.19 is merely illustrative.

Initially, tool 68 may be in a retracted position so that loop 30 is notreceived within hook 72 (FIG. 19).

As shown in FIG. 20, tool 68 may be advanced towards loop 30 indirection 74 so that hook 72 can receive loop 30 (FIG. 21). Tool 68 maythen be retracted in direction 78 to enlarge loop 30, as shown in FIG.22.

After forming loop 30, metal remover 80 may remove a portion of metalcoating 82 in a localized area of loop 30 to form open circuit 34. Asshown in FIG. 23, for example, metal remover 80 may be a metal sheaththis is advanced over shaft 70 and hook 72 of tool 68 until cutting edge86 of the sheath cuts away coating 82 from yarn 24. This leaves aportion of yarn 24 in loop 30 between loop portions 30-1 and 30-2 freeof metal coating 82 (i.e., a gap is formed in metal coating 82), therebyforming open circuit 34, as shown in FIG. 24. The metal sheath may thenbe retracted in direction 78 to expose hook 72 and the tip of shaft 70,as shown in FIG. 25.

FIGS. 26, 27, and 28 show how component 26 may be advanced along tool 68and mounted on loop 30, as described in connection with FIGS. 9 and 10.Soldering, welding, conductive adhesive attachment techniques, crimping,or other suitable techniques may be used to attach and thereby shortterminals 28 of component 26 to the conductive material (metal coating82) in yarn 24 of loop 30.

FIG. 29 shows how loop 30 may appear after component 26 has been mountedto loop 30. The presence of open circuit 32 allows signals to beconveyed through component 26 using the conductive metal coating on theleft and right sections of yarn 24.

If desired, fabric 12 may be formed from multiple yarns 24 andtechniques such as intarsia and plating may be used to create fabric 12in which components 26 are located and/or made visible in selectedportions of fabric 12. For example, in an intarsia scheme, components 26may be attached to a first yarn and not to a second yarn. Areas offabric 12 in which it is desired to include components 26 may be formedusing the first yarn. Areas of fabric 12 in which it is not desired toinclude components 26 may be formed using the second yarn.

As another example, a plating technique of the type shown in FIGS. 30-35may be used to form fabric 12. Using this technique, components 26 onthe first yarn may be hidden from view in some areas of fabric 12 byplacing the second yarn in front of the first yarn and may be exposed toview in other areas of fabric 12 by placing the first yarn in front ofthe second yarn (as an example).

As shown in FIG. 30, needles 54A and 54B may be used in knitting fabric12 from first yarn 24A and second yarn 24B. Components 26 may be mountedon first yarn 24A using component mounting tool 68. Component mountingtool 68 may then be retracted in direction 78 (FIGS. 31 and 32).

As shown in FIG. 33, left needle 54A may be advanced so that latch 60Aof needle 54A clears loop 30B of yarn 24B and so that butt 58A of needle54A advances yarn 24B to a position where loop 30B of yarn 24B may begrasped by hook 64B of needle 54B. Needle 54A may then be retracted(FIG. 34).

As shown in FIG. 35, in completed fabric 12, loops formed from secondyarn 24B such as loop 30B may be placed in front of loops formed fromfirst yarn 24A such as loop 30A. Components 26 are mounted on loops 30A,so the arrangement of FIG. 35 allows second yarn loops 30B to covercomponents 26 on loops 30A (i.e., the layer of knitted fabric 12 formedfrom loops 30B will be on the outside of fabric 12 and will be visibleto a user, whereas the layer of knitted fabric 12 formed from loops 30Aand components 26 on loops 30A will be on the inside of fabric 12 andwill not be visible to a user). If desired, the relative positions ofloops 30A and 30B (and therefore the exposure of components 26) may bevaried as a function of position in fabric 12. In some areas, components26 may be hidden from view by an exterior layer of knitted loops,whereas in other areas, components 26 may be exposed to view and may beuncovered (i.e., not covered by loops 30B).

When hiding components 26, loops 30B may be formed from opaque materialon the outside of fabric 12 that blocks underlying loops 30A on theinside of fabric 12 from view. If desired, loops 30B may be formed fromtransparent material (e.g., clear low-haze material, translucentmaterial, colored transparent material, etc.). In this type ofconfiguration, light that has been emitted by components 26 (e.g.,light-based components such as light-emitting diodes) may pass throughoverlapping loops 30A or light that has passed through loops 30A may bereceived by components 26 (e.g., light-based components such as lightdetectors). If desired, some of the loops in fabric 12 may be formedfrom opaque material and some of the loops in fabric 12 may be formedfrom transparent material. Configurations in which all of yarns infabric 12 are opaque or are transparent may also be used.

The foregoing is merely illustrative and various modifications can bemade by those skilled in the art without departing from the scope andspirit of the described embodiments. The foregoing embodiments may beimplemented individually or in any combination.

What is claimed is:
 1. A knit fabric comprising: a first set ofinterlocking loops of yarn, wherein the first set of interlocking loopsof yarn comprises a conductive portion at a loop in the first set ofinterlocking loops; a second set of interlocking loops of yarn; and anelectrical component disposed between the first set of interlockingloops of yarn and the second set of interlocking loops of yarn andhaving a terminal electrically shorted to the conductive portion at theloop.
 2. The knit fabric defined in claim 1, wherein the first set ofinterlocking loops of yarn comprises an additional conductive portion atthe loop and the electrical component has an additional terminalelectrically shorted to the additional conductive portion.
 3. The knitfabric defined in claim 2, wherein the first set of interlocking loopsof yarn comprises an insulating portion at the loop.
 4. The knit fabricdefined in claim 3, wherein the insulating portion separates theconductive portion from the additional conductive portion.
 5. The knitfabric defined in claim 1, wherein the conductive portion is formed froma conductive coating on an insulating core at the loop.
 6. The knitfabric defined in claim 1, wherein the electrical component comprises anintegrated circuit.
 7. The knit fabric defined in claim 1, wherein theelectrical component comprises a light-emitting diode.
 8. The knitfabric defined in claim 1, wherein the electrical component isconfigured to receive a signal from the conductive portion through theterminal.
 9. A fabric-based item comprising: fabric having a firstfabric layer and a second fabric layer that overlaps the first fabriclayer; and an electrical component electrically coupled to the firstfabric layer, configured to convey a signal across the first fabriclayer, and interposed between the first fabric layer and the secondfabric layer.
 10. The fabric-based item defined in claim 9, wherein thefirst fabric layer comprises a conductive strand of material and theelectrical component is electrically connected to the conductive strandof material.
 11. The fabric-based item defined in claim 9, wherein thefirst fabric layer is formed from a first yarn and the second fabriclayer is formed from a second yarn.
 12. The fabric-based item defined inclaim 9, wherein first fabric layer comprises a first set of loops, thesecond fabric layer comprises a second set of loops that overlap thefirst set of loops, and the electrical component is interposed betweenthe first set of loops and the second set of loops.
 13. The fabric-baseditem defined in claim 9, wherein the second fabric layer is formed fromopaque material.
 14. The fabric-based item defined in claim 9, whereinthe second fabric layer is formed from transparent material.
 15. Amethod of forming a fabric-based item, comprising: knitting strands ofmaterial to form a fabric with a knitting system; and while knitting thestrands with the knitting system, attaching an electrical component tofirst and second conductive portions of the strands, wherein theelectrical component is configured to carry a signal between the firstconductive portion of the strands and the second conductive portion ofthe strands.
 16. The method defined in claim 15, wherein knitting thestrands comprises forming loops using the strands.
 17. The methoddefined in claim 16, wherein attaching the electrical component to thefirst and second conductive portions of the strands while knitting thestrands with the knitting system comprises forming a loop in the loopsusing the strands with the knitting system after attaching theelectrical component to the first and second conductive portions of thestrands.
 18. The method defined in claim 17, wherein attaching theelectrical component to the first and second conductive portions of thestrands while knitting the strands with the knitting system comprisesforming an additional loop in the loops using the strands with theknitting system before attaching the electrical component to the firstand second conductive portions of the strands.
 19. The method defined inclaim 15, wherein the electrical component comprises first and secondterminals that are electrically connected to the first and secondconductive portions, respectively.
 20. The method defined in claim 15,wherein knitting the strands of material to form the fabric with theknitting system comprises: forming a first portion of the fabric usingthe strands before attaching the electrical component to the first andsecond conductive portions of the strands; and forming a second portionof the fabric using the strands after attaching the electrical componentto the first and second conductive portions of the strands.